Alethea Rea

Background
Wearable activity devices, widely used to monitor physical activity in non-injured populations, have shown potential in encouraging early ambulation and enhanced recovery in hospitalised patients. This study evaluated the accuracy of wearable devices in tracking step counts under simulated hospital conditions, seeking the optimal body location placement for individuals with altered gait.

Methods
This method comparison study involved healthy adults walking on a treadmill while performing slow and shuffling walking patterns. Twelve wearable devices were placed on the arm, waist, and leg, and their recorded step counts were compared to manual counts from filmed sessions, following Consumer Technology Association guidelines.

Results
The Apple Watch, particularly when worn on the waist, demonstrated the highest reliability and adaptability across walking patterns. Leg placement, which accounted for 10 of the top 20 device-position combinations, suggested that larger movement amplitudes improve step count accuracy, particularly during slow or altered gaits.

Conclusion
This study confirmed the Apple Watch to be the most accurate wearable step count device. The study provides new understanding as to the precision of commercially available devices and their placement, when aiming to improve and, or conduct research about, patient physical activity outcomes.

Obesity is linked to suboptimal breastfeeding outcomes, yet the relationships between maternal adiposity, breast anatomy, and milk production (MP) have not been investigated. We conducted ultrasound imaging to assess the breast anatomy of 34 lactating women. The amount of glandular tissue (glandular tissue representation (GTR)) was classified as low, moderate, or high. Number and diameters of main milk ducts and mammary blood flow (resistive index) were measured. Women completed a 24 h MP measurement and an obstetric/lactation history questionnaire. Body composition was measured with bioimpedance spectroscopy. Statistical analysis employed correlation networks. Multiple relationships were revealed, with later menarche correlating with minimal pubertal and pregnancy breast growth. A minimal breast growth was further correlated with lower mammary blood flow during lactation and lower numbers and smaller diameters of main milk ducts, which in turn correlated with a lower MP. Importantly, higher adiposity also correlated with minimal breast growth during pregnancy and low GTR and MP. Several modifiable and non-modifiable maternal factors may be associated with breast development and MP. Antenatal lactation assessment and intervention in high-risk women may ensure they reach their full lactation potential and inform future interventions, such as maintaining healthy adiposity.

Human milk contains a low biomass microbiome, which is thought to contribute to mammary and infant health. However, the determinants of the human milk microbiome across populations are poorly understood. Here, we characterized the microbiome of 266 milk samples collected from 208 mothers at 3 weeks and 3 months postpartum from the Growing Up in Singapore Toward healthy Outcomes (GUSTO) study, a multi-ethnic Asian cohort. Full-length 16S rRNA gene sequencing showed a substantial level of inter-individual variation, as well as temporal variation, highlighting the need for broad-scale longitudinal sampling in this field. Milk microbiome composition and diversity were associated with maternal, socioeconomic, and breastfeeding factors. In particular, intrapartum antibiotic prophylaxis and breastfeeding exclusivity modulated milk bacterial composition and diversity, even at 3 months postpartum. These results highlight the dynamic nature of the human milk microbiome and its relationship with clinical and breastfeeding factors, with potential implications for infant health.IMPORTANCEHuman milk exposes infants to a constant source of maternal bacteria that may influence the development of the infant immune system and gut microbiome. However, compared to other body niches, the human milk microbiome is relatively under-studied, and there is limited consensus on the factors driving variance in these bacterial communities. In this study, we performed in-depth microbiome profiling of milk samples from 208 mothers in a diverse Asian population, finding a high level of variation between individuals and over time. We found that factors such as delivery-related antibiotics, breastfeeding practices, and maternal lifestyle can influence which bacteria are present in milk. These findings suggest that the milk microbiome is not static, but dynamic and shaped by both medical and social factors. Understanding what drives variance in the milk microbiome could help inform strategies to support maternal and infant health, especially in the critical early months of life when microbial exposures can have long-term effects.

Donor human milk (DHM) provides myriad nutritional and immunological benefits for preterm and low birthweight infants. However, pasteurization leaves DHM devoid of potentially beneficial milk microbiota. In the present study, we performed milk microbiome transplantation from freshly collected mother's own milk (MOM) into pasteurized DHM. Small volumes of MOM (5%, 10%, or 30% v/v) were inoculated into pasteurized DHM and incubated at 37 °C for up to 8 h. Further, we compared microbiome recolonization in UV-C-treated and Holder-pasteurized DHM, as UV-C treatment has been shown to conserve important biochemical components of DHM that are lost during Holder pasteurization. Bacterial culture and viability-coupled metataxonomic sequencing were employed to assess the effectiveness of milk microbiome transplantation. Growth of transplanted MOM bacteria occurred rapidly in recolonized DHM samples; however, a greater level of growth was observed in Holder-pasteurized DHM compared to UV-C-treated DHM, potentially due to the conserved antimicrobial properties in UV-C-treated DHM. Viability-coupled metataxonomic analysis demonstrated similarity between recolonized DHM samples and fresh MOM samples, suggesting that the milk microbiome can be successfully transplanted into pasteurized DHM. These results highlight the potential of MOM microbiota transplantation to restore the microbial composition of UV-C-treated and Holder-pasteurized DHM and enhance the nutritional and immunological benefits of DHM for preterm and vulnerable infants. KEY POINTS: • Mother's own milk microbiome can be successfully transplanted into donor human milk. • Recolonization is equally successful in UV-C-treated and Holder-pasteurized milk. • Recolonization time should be restricted due to rapid bacterial growth.

To determine the effect of a two-week reduced fat and sugar and increased fibre maternal dietary intervention on the maternal faecal and human milk (HM) microbiomes.
Faecal swabs and HM samples were collected from mothers (n = 11) immediately pre-intervention, immediately post-intervention, and 4- and 8-weeks post-intervention, and were analysed using full-length 16S rRNA gene sequencing. Maternal macronutrient intake was assessed at baseline and during the intervention. Maternal fat and sugar intake during the intervention were significantly lower than pre-intervention (P=<0.001, 0.005, respectively). Significant changes in the bacterial composition of maternal faeces were detected after the dietary intervention, with decreases in the relative abundance of Bacteroides caccae (P=<0.001) and increases in the relative abundance of Faecalibacillus intestinalis (P = 0.006). In HM, the diet resulted in a significant increase in Cutibacterium acnes (P = 0.001) and a decrease in Haemophilus parainfluenzae (P=<0.001). The effect of the diet continued after the intervention, with faecal swabs and HM samples taken 4- and 8-weeks after the diet showing significant differences compared to baseline.
This pilot study demonstrates that short-term changes in maternal diet during lactation can alter the bacterial composition of the maternal faeces and HM. Clinical trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12619000606189). Website: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377188&isReview=true.

Early infancy is a critical period for immune development. In addition to being the primary food source during early infancy, human milk also provides multiple bioactive components that shape the infant gut microbiome and immune system and provides a constant source of exposure to maternal microbiota. Given the potential interplay between allergic diseases and the human microbiome, this study aimed to characterise the milk microbiome of allergic mothers. Full-length 16S rRNA gene sequencing was performed on milk samples collected at 3 and 6 months postpartum from 196 women with allergic disease. Multivariate linear mixed models were constructed to identify the maternal, infant, and environmental determinants of the milk microbiome. Human milk microbiome composition and beta diversity varied over time (PERMANOVA R2 = 0.011, p = 0.011). The season of infant birth emerged as the strongest determinant of the microbiome community structure (PERMANOVA R2 = 0.014, p = 0.011) with impacts on five of the most abundant taxa. The milk microbiome also varied according to the type of maternal allergic disease (allergic rhinitis, asthma, atopic dermatitis, and food allergy). Additionally, infant formula exposure reduced the relative abundance of several typical oral taxa in milk. In conclusion, the milk microbiome of allergic mothers was strongly shaped by the season of infant birth, maternal allergic disease phenotype, and infant feeding mode. Maternal allergic disease history and infant season of birth should therefore be considered in future studies of infant and maternal microbiota.

Diet is a key factor that shapes the gut microbiome. Maternal diet has been proposed as a potential modulator of the human milk microbiome. However, the effect of diet during lactation on the maternal microbiota remains unclear. This study, therefore, set out to determine the effect of a two-week reduced fat and sugar and increased fibre maternal dietary intervention on the maternal faecal and milk microbiota. Faecal swabs and human milk samples were collected from mothers (n = 11) immediately pre-intervention, immediately post-intervention, and 4- and 8-weeks post-intervention, and were analysed using full-length 16S rRNA gene sequencing. The maternal macronutrient intake was assessed across one week prior to the intervention using 24 h dietary recall and during the intervention using FoodWorks 10 Software. The maternal fat and sugar intake significantly decreased from pre-intervention (fat: 120.9 ± 39.4 g; sugar: 114.1 ± 40.9 g) to the first (fat: 52.9 ± 4.3 g, p < 0.001; sugar: 83.2 ± 5.1 g, p = 0.005) and second week of the intervention (fat: 52.3 ± 6.2 g, p < 0.001; sugar: 82.7 ± 6.5 g, p = 0.005). The dietary fibre intake significantly increased from pre-intervention (28.8 ± 8.3 g) to the first week of the intervention (34.6 ± 2.8 g, p = 0.012) but was not different in the second week of the intervention compared to pre-intervention. Significant changes in the bacterial composition of maternal faeces were detected after the dietary intervention, with decreases in the relative abundance of Bacteroides caccae and increases in the relative abundance of Faecalibacillus intestinalis. In human milk, a significant increase in Cutibacterium acnes and a decrease in Haemophilus parainfluenzae were detected. Significant differences in maternal faecal and human milk bacterial composition were maintained 4 to 8 weeks after the intervention. This pilot study demonstrates that short-term changes in maternal diet during lactation can alter the maternal faecal and human milk microbiota.

There is an inadequate understanding of the daily variations in hormones and macronutrients in human milk (HM), and sample collection protocols vary considerably from study to study. To investigate changes in these milk components across 24 h, 22 lactating women collected small milk samples before and after each breastfeed or expression from each breast. Test weighing was used to determine the volume of HM consumed in each feed. The concentrations of leptin, adiponectin, insulin, fat, and glucose were measured, and the intakes were calculated. A linear mixed model was fitted to assess within-feed and circadian variation in HM feed volume and concentration, and intakes of several components. The average infant intake of HM was 879 g/24 h. Significantly higher pre-feed concentrations were found for adiponectin and glucose and lower post-feed concentrations were found for insulin and fat. Significant circadian rhythms were displayed for leptin, adiponectin, insulin, glucose (both concentration and intake), fat concentration, and milk volume. These findings demonstrate the necessity for setting up standardised and rigorous sampling procedures that consider both within-feed and circadian variations in HM components to gain a more precise understanding of the impacts of these components on infant health, growth and development.

Continued breastfeeding attenuates maternal and infant risks associated with gestational diabetes mellitus (GDM), which may be more difficult after a GDM pregnancy, with reports of delayed secretory activation and reduced milk production. The total 24 h milk production cycle is not routinely measured; therefore, it is unclear whether reported low milk production is actual or perceived. We aimed to describe early lactation outcomes and 24 h milk production in women with GDM. Women with GDM-complicated pregnancies recorded early feeding practices. The 24 h cycle of milk production was measured at 3 weeks by weighing infants pre- and post-breastfeeds, as well as breast expression volumes. Electronic scales sensitive to 2 g were used. Low 24 h milk production was classified as <600 mL. For women with GDM (n = 40), the median time to the initiation of breastfeeding was 55 min, and delayed secretory activation (n = 24, 60%) was common. Most women achieved frequent milk removal (≥8 × 24 h) in the first 24 h after birth (n = 27, 68%) was at one week (n = 38, 95%) and three weeks postpartum (n = 36, 90%). However, median 24 h milk production was 639 mL (range 100–1220 mL), with low milk production measured in n = 16 (40%, range 100–592 mL). Conclusions: Delayed secretory activation and low milk production are more common in women with GDM despite regular milk removal from the breast, suggesting that altered endocrine pathways inherent to GDM may be implicated.

Animal models show a more rapid mammary gland response and more milk with subsequent lactations, as well as impairment of lactation performance by obesity. Whilst maternal obesity is linked to reduced breastfeeding initiation, breastfeeding confidence, and duration as well as early introduction of formula, maternal adiposity, breast anatomy and milk production (MP) have not been assessed in this population. Thirty-four lactating mothers 1–6 months postpartum and with BMI range of 17–35 kg/m2 participated in this study. We conducted ultrasound examination imaging to assess breast anatomy. The amount of glandular tissue (glandular tissue representation (GTR)) was classified as low, moderate, or high. Number and diameters of milk ducts as well as mammary blood flow (the resistive index) were measured. Maternal bra cup volume was calculated from current bra size. Maternal body composition was measured with bioimpedance spectroscopy. Mothers completed a questionnaire regarding their medical, obstetric and lactation history, and conducted a 24 h MP study to enable calculation of total volume, average and maximum feed volumes and breast storage capacity (24 h MP parameters). For statistical analysis, we used the correlation networks method (directions of multiple significant correlations are reported). Correlation networks show that pathways culminating in either high or low MP start as early as puberty. In this study, later menarche correlates with the absence of breast growth during both puberty and pregnancy, which further correlate with lower numbers of ducts and smaller diameters. Higher maternal adiposity correlates with larger bra cup volume (both correlate with absence of breast growth during pregnancy and low GTR) and lower 24 h MP parameters. Larger numbers of ducts and duct diameters correlate with higher parity and longer durations of previous lactations, and higher 24 h MP parameters. Mammary blood flow shows no correlations. Findings from this cross-sectional study corroborate animal studies showing that a number of modifiable and non-modifiable maternal factors may impact breast development and MP. Further research may inform interventions, such as maintaining healthy adiposity not only during pre-conception, pregnancy, and lactation, but as early as childhood and potentially infancy. Moreover, the results provide rationale for antenatal lactation assessment of women and intervention in high-risk mothers to ensure they reach their full lactation potential.